Stabilized cholesteric liquid crystals have high viscosity due to the presence of a large amount of chiral dopants and a corresponding strong twisting nature inherent in the chiral material. High viscosity, however, can undesirably increase the response time of these materials when used in electrooptic devices.
Materials have been added to nematic liquid crystals for reducing their viscosity. Nematic liquid crystal materials have drastically different properties than cholesteric liquid crystal materials. For example, cholesteric materials exhibit weakly scattering focal conic and reflecting twisted planar states which are stable in the absence of a field. One cannot predict the effect that additives for lowering the viscosity of nematic liquid crystals may have in a chiral nematic liquid crystal material.
The textures of chiral nematic materials make predicting their behavior difficult compared to nematics. The liquid crystal molecules of chiral nematic materials have directors that are helically oriented, which makes it difficult to conduct experiments such as measurements of dielectric constant and transmission. In view of the difficulty in measuring properties of cholesteric liquid crystal materials and the unpredictability in formulating compositions of such materials, the need remains for additives that can lower the viscosity of a chiral nematic liquid crystal material for use in a display device.